Rheumatoid arthritis is a fairly common crippling disease leading to deformity and loss of function of the joints. These effects are extremely painful and often include complete loss of function of the joints involved. If joints of the hands are involved, the afflicted patient may become totally incapable of caring for himself. Heretofore, prosthetic joints have been used to restore function to such hands. Such prosthetic joints have comprised a pair of oppositely projecting stem portions connected by a hinged center portion which bends. Typical of prior prosthetic joints is the Swanson prosthetic joint which is disclosed in U.S. Pat. No. 3,462,765.
The prior prosthetic joints may fail because of cracking or fragmentation of the stem portions or center portion due to the high forces imposed upon them incident to their bending in the hinged center portion. The prosthetic joint of the present invention handles these problems by more clearly simulating a natural finger joint and other upper extremity joints (example: wrist and elbow), and providing a prosthetic joint which offers minimal resistance and operates with very little friction since it employs a rolling action. Hence the prosthetic joint of the invention is subject to very little friction wear, has a long life, and also allows more forceful motion.